Terhardt, E. (1995). Music perception in the auditory hierarchy. In: Music and the Mind Machine - The Psychophysiology and Psychopathology of the Sense of Music (Steinberg, R., ed.), Springer, Berlin/Heidelberg, 81-87

It is outlined that the rigorous and systematic organization of music both in the time domain and the low-high domain is neither arbitrary nor purely artificial, but rather is archetypical for the essential principles of the auditory acquistion of information. The principles that govern perception of music can be put into the context of sensory information acquisition in general. Common to all systems of information acquisition and -processing are the principles of discretization, hierarchical organization, and knowledge-based decision on all levels of the auditory hierarchy. Knowledge-based decision-making on all hierarchical levels implies that each of the hierarchical layers of processing is to a considerable extent autonomous. Discretization in the time domain becomes manifest in the notion that an essentially continuous signal (such as speech) is perceived as a sequence of events. In the pitch domain, discretization is manifest in the existence of discrete musical pitches. In vision, an analogous case of discretization is the formation of contours. In fact, for visual acquisition of information contours play exactly the same role as do spectral pitches for auditory acquisition of information. Both types of contour convey robust information about external objects. In this sense one may regard pitch as auditory contour. Likewise, temporal acoustic events can be regarded as being reflected by temporal auditory contours. Several types of contour (both visual and auditory) ordinarily appear on any level of the sensory hierarchy in such a way that higher-level contours are dependent on lower-level contours. In these general terms, music appears as a "play with contours" which obeys and reflects the universal principles of sensory acquisition of information.

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